The present invention relates to a photo-magnetic type recording/reproducing apparatus which is applicable to an external storage of a computer or the like, and more particularly to a power transmission mechanism for driving a magnetic field generating means in such a photo-magnetic type recording/reproducing apparatus.
Recently, of recording/reproducing systems for recording, reproducing and erasing information by using laser light, a so-called photo-magnetic disc apparatus is known which records and erases information with a magnetic field being applied to a recording medium (photo-magnetic disc), the photo-magnetic disc being detachable from the photo-magnetic disc apparatus and encased in a case to constitute a cartridge for protection of its recording surface. For applying the magnetic field to the photo-magnetic disc, a magnetic field generating means comprising an electro-magnet is provided at the vicinity of the recording surface. However, a drive source such as an electric motor is required to be exclusively provided for moving the magnetic field generating means, thus making difficult the size-reduction of the apparatus.